CATALOGUE OF CANADIAN PLANTS. 397 



(1825.) A. RETROPLEXUS, Linn. Pigweed. 



Apparently unknown in Nova Scotia, but common at Fredericton, 

 N.B. Introduced and well established in all well manured soils through- 

 out Ontario. It has also reached the North-west and penetrated to 

 the summit of the Rocky Mountains, along the Canadian Pacific Rail- 

 way, and will be a perpetual source of trouble to western farmers. 

 Common at Victoria, B.C. ( Fletcher.} 



(1826.) A. ALBUS, Linn. 



Naturalized on waste heaps near towns and extensively spreading 

 along railways throughout the whole country, being found in the North- 

 west and British Columbia wherever railway construction is going on. 



(1827.) A. BLITOIDES, Watson. 



Well established at Point Edward near Sarnia, Ont., Sept. 15, 1884. 

 Possibly a railway introduction. (J". M. Macoun.} 



504. ACNIDA, Linn. (WATER HEMP.) 



(1828.) A. ruscocarpa, Gray. 



Montelia tamariscina, Gray, Man. 413, 1868. Macoun's Cat. No. 1506. 

 A. rusocarpa, Michx. Pursh, Fl. I., 205, in part. 

 A. altissima, Michx. Herb. Vide Gray. 



A tall dioecious plant, growing on alluvium in river bottoms. 

 Hull, P.Q. (Fletcher FL Ott.} In muddy places along the Nation 

 River at Casselman, west of the Canada Atlantic Railway ; also in 

 the Mill Pond at Madoc Village, North Hastings and along the Salmon 

 River at Shannonville, east of Belleville, Ont. (Macoun.} Maiden, 

 Ont. (Maclagan.} Low flats along the River Thames, London, Ont. 

 (Sounders & Burgess.} 



(1829.) A. tuberculata, Moq. 



A. rusocarpa, Moq. DC. Prod. XIIL, II., 278. 



A. cannaUna, var. concatenate, Moq. DC. Prod. XIIL, II., 278. 



Montelia tamariscina, var. concatenate, Gray, Man. 413, 1868. 



This form has the flowers, on the lower part of the stem, gathered 

 into close clusters in the axils of the leaves. On sand along the Ottawa 

 River at Brittania, near Ottawa. (Macoun.} Low, wet fields, London, 

 Ont. (Burgess.} 



